Research Note

A multi-site campaign to detect the transit of the second planet in HAT-P-13^⋆

¹ Konkoly Observatory of the Hungarian Academy of Sciences, PO Box 67, 1525 Budapest, Hungary
e-mail: szgy@konkoly.hu; kiss@konkoly.hu
² Department of Experimental Physics and Astronomical Observatory, University of Szeged, 6720 Szeged, Hungary
³ Hungarian Eötvös Fellow, Department of Astronomy, University of Texas at Austin, 1 University Station, Austin, TX 78712, USA
⁴ Sydney Institute for Astronomy, School of Physics A28, University of Sydney, NSW 2006, Australia
⁵ INAF - Osservatorio Astrofisico di Catania, via Santa Sofia 78, 95123 Catania, Italy
⁶ Graduate Institute of Astronomy, National Central University, No. 300, Jhongda Rd, Jhongli City, Taoyuan County 32001, Taiwan

Received: 8 June 2010
Accepted: 23 September 2010

Abstract

Aims. A possible transit of HAT-P-13c had been predicted to occur on 2010 April 28. Here we report on the results of our multi-site campaign organised to detect the event.

Methods. CCD photometric observations were carried out at five observatories in five countries. We reached 30% time coverage in a 5-day interval centered on the suspected transit of HAT-P-13c. Two transits of HAT-P-13b were also observed.

Results. No transit of HAT-P-13c was detected during the campaign. By a numerical experiment with 10⁵ model systems, we conclude that HAT-P-13c is not a transiting exoplanet with a significance level from 65% to 72%, depending on the planet parameters and the prior assumptions. We present two times of transit of HAT-P-13b ocurring at BJD 2455141.5522 ± 0.0010 and BJD 2455249.4508 ± 0.0020. The TTV of HAT-P-13b is consistent with zero within 0.001 days. The refined orbital period of HAT-P-13b is 2.916293 ± 0.000010 days.